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<h3>Notes:</h3><br>

<p><p style="direction:ltr;"><font color="#000000">We check the similarity of Composable UDT by comparing CTCP and Linux TCP. Over a 1Gb/s link, we start 1 to 64 flows of CTCP and Linux TCP respectively. We record the throughput, fairness index, and stability index, which covers the majority of a transport protocol's performance properties.</font></p>
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<p style="direction:ltr;"><font color="#000000">This table lists these values for both CTCP and Linux TCP. We can see that both implementations have similar performance. However, CTCP does have a CPU usage overhead, as we can see that at 64 parallel flows, CTCP has smaller throughput than Linux TCP.</font></p>
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<p style="direction:ltr;"><font color="#000000">The overhead comes from additional memory copies, context switches, and user thread synchronizations. This is especially significant at the sender side.</font></p>
<p style="direction:ltr;"><font color="#000000">This is one shortcoming of Composable UDT, but we argue that in many situations, this is not a problem. For example, this overhead only exists when comparing it to kernel implementations; other user space implementations have the same overhead too.</font></p>
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